Evolutionary Genetics Field trip Introduction: In the experiment, we will be the convention is that you are writing in the present about your aims, for an experiment which has been done. Hence 'we planned to collect' is better. collecting snails from different sites and observing the different patterns and colours explaining polymorphism they don't explain polymorphism. They are a consequence perhaps. in snails. Polymorphism occurs where there are multiple alleles of a gene within a population, usually expressing different phenotypes. Snails (especially Cepaea hortensis and Cepaea nemoralis) have been studied for decades in great detail as they are highly polymorphic and therefore good model organisms, they are easier to study than humans as they have a small dispersal distance which means genetic patterns will be localised and be on a scale easy to study. Cepaea (snails) consist of a simple system in terms of variation vague. What does that mean? How do we know? citation? but from intense study of the Cepaea, scientists who, citation? have learnt that there are many types of evolutionary forces that act upon the Cepaea that causes the polymorphism in the snails.
These processes are important for polymorphism wider importance? and can have different effects depending on which locus they act upon. Moreover, a different effect can even be seen if this force acts on the same locus within a different population clarify e.g. with an examples. This means that each Cepaea population is unique depending on the evolutionary forces that are acting upon it so?.
We can explain polymorphism by collecting snails from different sites comprising of different alleles poorly drafted, the sites don't consist of allelels, eg. different banding patterns and colours, from each site and comparing them. We will see above on tense collect snails from 2 or 3 different sites such as woodland, grassland and shrubs and record the different types of snails (colour and banding pattern) we saw from each site and form a table to compare the difference and form a null hypothesis based on the results no,no you need to formulate your hypothesis first, which guides the experimental design, and they hypothesis is then evaluated in light of the results. The hypothesis is was that the different sites will have the same frequencies of phenotype. In other words, there will be no patterns to suggest that there we should find more yellow snails in a certain area than another, it will be similar throughout you are confusing your hypotheses about the underlying processes (drift, gene flow, selection) and the results (differences in phenotype frequency). If this is true than the observable phenotype in the different sites will have approximately the same number of snails.
However, if this is not the case and there are different ranges of the observable phenotypes (polymorphism) then the difference can be due to genetic drift and selection or gene flow (the transfer of genes from one population to another). vague. Needs more precision In order to test what caused the polymorphism to arise we will need to analyse the phenotypic differences and similarities between the snails. vague and does not explain how Gene flow increases genetic diversity by introducing alleles from neighbouring populations especially if selection occurs in the populations. so.. how has this informed your experimental design?
Colour
Bands
Live adults
Live Sub adults
Dead Adults
Dead Sub adults
Brown
0
-
-
-
-
1 – 2
-
-
10
-
3 – 5
-
-
-
-
Pink
0
-
-
-
-
1 – 2
-
-
-
-
3 – 5
-
-
16
-
Yellow
0
-
-
-
-
1 – 2
-
-
4
-
3 – 5
-
-
-
-
Total:
0
0
0
30
0
Colour
Bands
Live adults
Live Sub adults
Dead Adults
Dead Sub adults
Brown
0
-
-
-
-
1 – 2
-
-
2
-
3 – 5
-
-
-
-
Pink
0
-
-
-
-
1 – 2
-
-
14
-
3 – 5
-
-
-
-
Yellow
0
-
-
-
-
1 – 2
-
-
12
-
3 – 5
-
-
2
-
Total:
0
0
0
30
0
The first table shows the data collected from a woodland area and the second shows the data collected from clear land. References
Jones. (1977). Polymorphism in Cepaea: A Problem with Too Many Solutions? Ann Rev Ecol Syst. 8 (3), 109-143.
Introduction:
In the experiment, we will be the convention is that you are writing in the present about your aims, for an experiment which has been done. Hence 'we planned to collect' is better. collecting snails from different sites and observing the different patterns and colours explaining polymorphism they don't explain polymorphism. They are a consequence perhaps. in snails. Polymorphism occurs where there are multiple alleles of a gene within a population, usually expressing different phenotypes. Snails (especially Cepaea hortensis and Cepaea nemoralis) have been studied for decades in great detail as they are highly polymorphic and therefore good model organisms, they are easier to study than humans as they have a small dispersal distance which means genetic patterns will be localised and be on a scale easy to study. Cepaea (snails) consist of a simple system in terms of variation vague. What does that mean? How do we know? citation? but from intense study of the Cepaea, scientists who, citation? have learnt that there are many types of evolutionary forces that act upon the Cepaea that causes the polymorphism in the snails.
These processes are important for polymorphism wider importance? and can have different effects depending on which locus they act upon. Moreover, a different effect can even be seen if this force acts on the same locus within a different population clarify e.g. with an examples. This means that each Cepaea population is unique depending on the evolutionary forces that are acting upon it so?.
We can explain polymorphism by collecting snails from different sites comprising of different alleles poorly drafted, the sites don't consist of allelels, eg. different banding patterns and colours, from each site and comparing them. We will see above on tense collect snails from 2 or 3 different sites such as woodland, grassland and shrubs and record the different types of snails (colour and banding pattern) we saw from each site and form a table to compare the difference and form a null hypothesis based on the results no,no you need to formulate your hypothesis first, which guides the experimental design, and they hypothesis is then evaluated in light of the results. The hypothesis is was that the different sites will have the same frequencies of phenotype. In other words, there will be no patterns to suggest that there we should find more yellow snails in a certain area than another, it will be similar throughout you are confusing your hypotheses about the underlying processes (drift, gene flow, selection) and the results (differences in phenotype frequency). If this is true than the observable phenotype in the different sites will have approximately the same number of snails.
However, if this is not the case and there are different ranges of the observable phenotypes (polymorphism) then the difference can be due to genetic drift and selection or gene flow (the transfer of genes from one population to another). vague. Needs more precision In order to test what caused the polymorphism to arise we will need to analyse the phenotypic differences and similarities between the snails. vague and does not explain how Gene flow increases genetic diversity by introducing alleles from neighbouring populations especially if selection occurs in the populations. so.. how has this informed your experimental design?
The first table shows the data collected from a woodland area and the second shows the data collected from clear land.
References
Jones. (1977). Polymorphism in Cepaea: A Problem with Too Many Solutions? Ann Rev Ecol Syst. 8 (3), 109-143.
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